The PersistenceManager class is a basic persistence manager that
is backed by a local shared object named FxAppCache.
When initialized, it loads a local shared object that matches its id.
If a local shared object is not found, it is created.

When storing values using the manager, it is important that all
values can be properly be written to a shared object.
Complex objects that store classes or non-standard flash primitives
must implement flash.net.IExternalizable interface to work properly.
Saving incompatible objects does not cause an RTE, but creates
undefined behavior when the data is read back.